Production of substantially odorless alkyl aryl sulfonate detergents



2,757,195 PRODUCTION OF SUBSTANTIALLY ODORLESS ALKYL ARYL SULFONATEDETERGENTS Richard Dale Stayner, Berkeley, Calif., assignor toCalifornia Research Corporation, San Francisco, Calif., a

corporation of Delaware No Drawing. Application July 2, 1952,

Serial No. 296,930 3 Claims. (Cl. 260-505) This invention relates to aprocess for producing substantially odorless alkyl aryl sulfonatedetergents and to an alkyl aryl hydrocarbon composition convertible tosubstantially odorless sulfonate detergent by conventional processingmethods.

Synthetic detergents are currently produced and consumed in very largequantities. "The great bulk of synthetic detergents now manufactured andsold are alkyl aryl sulfonate detergents prepared by reacting an alkylbenzene containing 10 to 18 carbon atoms in the alkyl group withconcentrated sulfuric acid and neutralizing the sulfonic acids thusproduced. The alkyl benzenes employed as raw materials are, for the mostpart, polypropylene benzenes prepared by alkylating benzene with apropylene polymer fraction containing from 10 to 18 carbon atoms in thepolymer chains, and keryl benzenes prepared by chlorinating kerosene andcondensing the resulting alkyl chloride with benzene.

It has been observed that upon completion of the sulfonation andneutralization steps the detergents, especia1- ly if produced from abranched-chain alkyl benzene, may have a rather unpleasant odor of thecharacter of neutralized petroleum sludge. In sulfuric acid treatment ofpetroleum fractions this odor is often encountered in the neutralizedacid sludge. When the alkyl aryl sulfonate detergent is blended withbuilders -to produce a final detergent composition containing from 15 to25% of active detergent material, the odor level is reduced, but isstill sufiiciently high to give rise to consumer complaints.

Actually, two types of odor difficulty have been experienced with alkylaryl sulfonate detergents: neutralized sludge type odor, which emanatesfrom the detergent material immediately upon completion of thesulfonation and neutralization steps; and a rancid odor which developson storage. The development of rancidity on storage appears to be morecharacteristic of the keryl benzene detergents than of the polypropylenebenzene type detergents. With the former, rancidity develops rapidlyupon storage at fairly high temperature, while the latter develops arancid odor only infrequently and then following long storage at hightemperature in the presence of very appreciable quantities of moisture.The rancid odor developed on storage is discussed in U. S. Patent No.2,469,376, which teaches that the development of such an odor may beprevented by the addition of an amino aromatic compound to theneutralized detergent slurry before it is dried.

The present invention is not concerned with the rancid odor which isdeveloped on storage, but rather with the neutralized sludge odor whichis characteristic of the freshly prepared detergent. It has now beenfound that a substantially odorless alkyl aryl sulfonate detergent maybe produced by sulfonating a branched-chain alkyl benzene in thepresence of from 0.02 to 0.1% by weight of ortho-phenylenediamine,para-phenylenediamine, or mixtures of orthoand para-phenylenediamine,based on the alkyl benzene hydrocarbon material.

The invention may be better understood from the following examples:

2,757,195 Patented July 31, 1956 Example 1 A polypropylene benzenehydrocarbon of the type described in U. S. Patent No. 2,477,382 andboiling in the" amount snfiicient to reduce the concentration of theun-' reacted sulfuric acid to by weight. The diluted. reaction mixturewas settled for a period of two hours at; F. An upper organic layerconsisting predomi--- nantly of alkyl benzene sulfonic acids and a loweraqueous layer consisting predominantly of aqueous sulfuric acid wereformed. The layers were separated and. the alkyl benzene sulfonic acidlayer was neutralized with: sodium hydroxide. In this example and in thefollowing examples, ammonium hydroxide, potasium hydroxide or? magnesiumhydroxide may be used to neutralize the sul-- fonic acid layer withoutany effect on the observed odorcharacter of the product. An aqueoussolution of the neutral product having a sodium alkyl benzenesulfonate-v content of 10% by weight was tested for odor immedi-- atelyand found to have a strong odor of the type generally characteristic ofneutralized sludge. A portion of the neutral product was drum-dried andwas observed ta have a strong sludge odor.

Example 2 The process described in Example 1 was repeatedl. Beforeadding the acid to the alkyl benzene hydrocarbon,. 0.001% by Weight ofpara-phenylenediamine was dis-- solved in the alkyl aryl hydrocarbon.Both the 10% aqueous solution of the neutral product and the dry neutralproduct still exhibited a strong sludge odor.

Example 3 Example 1 was repeated. 0.01% by weight ofparaphenylenediamine was dissolved in the alkyl benzene. hydrocarbonprior to addition of the sulfuric acid. The, odor of a 10% aqueoussolution of the neutral product produced was substantially less intensethan the odorof the 10% solution produced in Example 1 and was of thesame general character. The odor of the dry neutral product wassimilarly reduced in intensity.

Example 4 Example 1 was repeated. 0.022% by weight ofparaphenylenediamine was dissolved in the alkyl benzene hy-- drocarbonprior to the addition of the acid. A 10% solution of the neutral producthad a very mild odor, the.- sludge character being barely perceptible.

Example 5 Example 1 was repeated. Immediately after the addition of theacid to the alkyl benzene hydrocarbon and before the two-hour digestionperiod, para-phenylenediamine amounting to 0.05% by weight based on thealkyl benzene hydrocarbon was added to the mixture. A 10% solution ofthe neutral product was essentially odor-- less. The dry neutral productwas also essentially odorless.

Example 6 Example 5 was repeated, substituting ortho-phenylenew diaminefor para-phenylenediamine. A 10% solution of the neutral product wasessentially odorless. The dry neutral product was also essentiallyodorless.

Example 7 Example 8 Example 1 was repeated. 0.1% by weight ofparaphenylenediamine was suspended in the alkyl benezene hydrocarbonprior to the addition of the acid. A solution of the neutral product wasessentially odorless.

Example 9 Example 1 was repeated omitting the water dilutionandacid-settling steps. 0.05% by weight of para-phenylenediaminewasdispersed in. the alkyl benzene hydrocarbon prior to the addition of theacid. The sulfonation reaction product was neutralized immediately uponcompletion of the sulfonation reaction. The dry neutral product had avery. mild odor, but had a definite gray color indicating that the waterdilution and acid-settling steps should be taken if a pure white productis desired.

Orthoor para-phenylenediamine is similarly effective in reducing theodor level of the fresh sodium alkyl benzene sulfonate obtained fromkeryl benzenes containing 10 to 18 carbon atoms in the alkyl group.

The action of orthoor para-phenylenediamine in reducing the odor levelof freshly prepared sodium alkyl benzene sulfonates. is specific. Otheramino aromatic compounds are not effective. When Example 6 is repeatedusing meta-phenylenediamine, the odor of the neutral product ispracticaly indistinguishable from the odor of the product in Example 1.

Orthoor para-phenylenediamine obviously acts to inhibit the formation ofthose side reaction products during the sulfonation step which impartthe undesirable odor to the finished detergent. The manner in whichorthoor paraphenylenediamine accomplishes this result is not understood.An intermediate compound of orthoor para-phenylenediamine and sulfuricacid may be formed. 'It is observed that when orthoorparaphenylenediamine is added to the sulfuric acid alone, a purple colorimmediately develops, indicating reaction of some sort. However theorthoor para-phenylenediamine may function to accomplish the resultindicated above, it appears that no orthoor para-phenylenediamine ispresent as such in the final detergent product. Further, if the waterdilution and acid-settling steps are employed, the final detergentproduct also appears to be free of any derivative of orthoorpara-phenylenediamine. Due to the known skin sensitization reaction ofparaphenylenediamine, it is desirable to practice acid dilution or toemploy some other means of reducing the amount of para-phenylenediamineor its reaction products to a minimum. The use of orthoorpara-phenylenediamine in the manner above described is effective only toinhibit the development of the neutralized acid sludge odor in thefreshly prepared detergent. If the neutral detergent product is storedat high temperature in the presence of an appreciable amount of moisturefor a long period of time, a rancid odor quite different from the odorof the freshly prepared detergent can be developed. As a practicalmatter the development of rancidity is not a problem with alkyl arylsulfonate detergents prepared from polypropylene benzene. If it isdesired to prepare a detergent from the keryl benzene which is odorlessimmediately after preparation, and which does not develop a rancid odorupon storage, the sulfonation should be conducted in the presence oforthoor paraphenylenediamine in the manner described, and a small amountof hydroquinone, usually from 0.001 to 0.005% by weight based on thesodium alkyl benzene sulfonate should be added to the neutral productbefore drying it.

As indicated in the examples, orthoor para-phenylenediamine, to beeffective in suppressing the development of the neutralized sludge typeodor in the freshly prepared detergent, must be present while thesulfonation reaction is going on. It may be added to the alkyl benzenehydrocarbon prior to mixing the hydrocarbon and acid, or it may be addedvery shortly after mixing the hydrocarbon and acid while the sulfonationreaction is under way. If the orthoor paraphenylenediamine is not addeduntil the sulfonation reaction is essentially completed, it isineffective.

At least 0.01% by weight of orthoor para-phenylenediamine should beadded to the alkyl benzene if any appreciable odor improvement is to beachieved. Preferably, the amount of orthoor paraphenylenediamine addedis in the range from 0.02 to 0.1% based on the alkyl benzenehydrocarbon. Orthoand para-phenylenediamine are only sparingly solublein alkyl benzenes having 10 to 18 carbon atoms in the alkyl chain. Atroom temperature a saturated solution contains about 0.025% by weight.This quantity is sufficient to effect a marked improvement in the odorof the fresh detergent prepared by sulfonation and neutralization. Asubstantially saturated solution of orthoor paraphenylenediamine in thealkyl benzene constitutes an excellent raw material from which toproduce alkyl aryl sulfonate detergents of good odor. Such solutions canbe conveniently prepared by the manufacturer of the alkyl benzenehydrocarbon and shipped to detergent manufacturers who may directlysulfonate the solution, neutralize the resultant sulfonic acid, add thedesired builders, and dry the product.

The solubility of orthoor para-phenylenediamine can be increased withoutimpairing its effectiveness either by introducing an alkyl group intothe nucleus to replace a nuclear hydrogen atom, or by replacing one ofthe amino hydrogens with an alkyl group.

I claim:

1. In a process for producing an alkyl aryl sulfonate detergent bysulfonating an alkyl benzene hydrocarbon having 10 to 18 carbon atoms inthe alkyl group with concentrated sulfuric acid, settling thesulfonation reaction product to separate a sulfonic acid layer and anunreactcd sulfuric acid layer, neutralizing the sulfonic acid layer anddrying the neutral product, the improvement which comprises dispersingfrom 0.02 to 0.1% by weight or" at least one aromatic amine of the groupconsisting of ortho-phenylenediamine and para-phenylenediamine in thehydrocarbon before the sulfonation reaction is complete.

2. A process for producing an alkyl aryl sulfonate detergent whichcomprises sulfonating an alkyl aryl hydrocarbon having 10 to 18 carbonatoms in the alkyl group with concentrated sulfuric acid in the presenceof 0.02 to 0.01% by weight of at least one aromatic amine of the groupconsisting of ortho-phenylenediamine and para-phenylenediamine based onthe hydrocarbon, diluting the reaction product mixture with water,settling the diluted mixture to separate an upper organic phasecomprising sulfonic acids and essentially free of orthoandpara-phenylenediamine and a lower aqueous layer and neutralizing theupper layer with a base.

3. A composition suitable for sulfonation to produce a sulfonationproduct free of sludge odor, comprising an alkyl benzene hydrocarbonhaving 10 to 18 carbon atoms in the alkyl group in which is incorporated0.01 to 0.1% by weight of at least one aromatic amine of the groupconsisting ortho-phenylenediam'ine and para-phenylenediamine.

Crowder Dec. 30, 1941 Flett May 10, 1949

1. IN A PROCESS FOR PRODUCING AN ALKYL ARYL SULFONATE DETERGENT BYSULFONATING AN ALKYL BENZENE HYDROCARBON HAVING 10 TO 18 CARBON ATOMS INTHE ALKYL GROUP WITH CONCENTRATED SULFURIC ACID, SETTLING THESULFONATION REACTION PRODUCT TO SEPARATE A SULFONIC ACID LAYER AND ANUNREACTED SULFURIC ACID LAYER, NEUTRALIZING THE SULFONIC ACID LAYER ANDDRYING THE NEUTRAL PRODUCT, THE IMPROVEMENT WHICH COMPRISES DISPERSINGFROM 0.02 TO 0.1% BY WEIGHT OF AT LEAST ONE AROMATIC AMINE OF THE GROUPCONSISTING OF ORTHO-PHENYLENEDIAMINE AND PARA-PHENYLENEDIAMINE IN THEHYDROCARBON BEFORE THE SULFONATION REACTION IS COMPLETE.